Exercise 12 Review Muscles of the Lower Limb Answers
Learning Objectives
By the finish of this section, you lot volition be able to:
- Identify the appendicular muscles of the pelvic girdle and lower limb
- Identify the movement and function of the pelvic girdle and lower limb
The appendicular muscles of the lower trunk position and stabilize the pelvic girdle, which serves equally a foundation for the lower limbs. Insufficiently, there is much more movement at the pectoral girdle than at the pelvic girdle. There is very piddling movement of the pelvic girdle because of its connection with the sacrum at the base of the axial skeleton. The pelvic girdle is less range of motion because it was designed to stabilize and support the trunk.
Muscles of the Thigh
What would happen if the pelvic girdle, which attaches the lower limbs to the torso, were capable of the same range of motion as the pectoral girdle? For i thing, walking would expend more free energy if the heads of the femurs were not secured in the acetabula of the pelvis. The trunk's center of gravity is in the surface area of the pelvis. If the heart of gravity were not to remain fixed, standing up would be difficult as well. Therefore, what the leg muscles lack in range of move and versatility, they make upward for in size and power, facilitating the body'south stabilization, posture, and movement.
Gluteal Region Muscles That Move the Femur
Most muscles that insert on the femur (the thigh bone) and movement it, originate on the pelvic girdle. The psoas major and iliacus make up the iliopsoas group. Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group. The gluteus maximus is the largest; deep to the gluteus maximus is the gluteus medius, and deep to the gluteus medius is the gluteus minimus, the smallest of the trio (Figure eleven.29 and Effigy 11.30).
Figure 11.29 Hip and Thigh Muscles The large and powerful muscles of the hip that motility the femur generally originate on the pelvic girdle and insert into the femur. The muscles that move the lower leg typically originate on the femur and insert into the basic of the knee articulation. The anterior muscles of the femur extend the lower leg but also aid in flexing the thigh. The posterior muscles of the femur flex the lower leg just also aid in extending the thigh. A combination of gluteal and thigh muscles as well adduct, housebreak, and rotate the thigh and lower leg.
Effigy 11.30 Gluteal Region Muscles That Move the Femur
The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts equally a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh. It likewise helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract (band), making it taut. Deep to the gluteus maximus, the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris laterally rotate the femur at the hip.
The adductor longus, adductor brevis, and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot. The adductor longus flexes the thigh, whereas the adductor magnus extends it. The pectineus adducts and flexes the femur at the hip as well. The pectineus is located in the femoral triangle, which is formed at the junction between the hip and the leg and also includes the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes.
Thigh Muscles That Move the Femur, Tibia, and Fibula
Deep fascia in the thigh separates it into medial, inductive, and posterior compartments (see Figure xi.29 and Figure xi.31). The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip. Along with the adductor longus, adductor brevis, adductor magnus, and pectineus, the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee.
Figure 11.31 Thigh Muscles That Move the Femur, Tibia, and Fibula
The muscles of the inductive compartment of the thigh flex the thigh and extend the leg. This compartment contains the quadriceps femoris group, which actually comprises four muscles that extend and stabilize the knee. The rectus femoris is on the anterior attribute of the thigh, the vastus lateralis is on the lateral aspect of the thigh, the vastus medialis is on the medial aspect of the thigh, and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris. The tendon common to all four is the quadriceps tendon (patellar tendon), which inserts into the patella and continues below it as the patellar ligament. The patellar ligament attaches to the tibial tuberosity. In add-on to the quadriceps femoris, the sartorius is a band-similar muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia. This versatile muscle flexes the leg at the knee and flexes, abducts, and laterally rotates the leg at the hip. This musculus allows us to sit cross-legged.
The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh. The three long muscles on the back of the knee are the hamstring group, which flexes the knee. These are the biceps femoris, semitendinosus, and semimembranosus. The tendons of these muscles form the popliteal fossa, the diamond-shaped space at the back of the knee.
Muscles That Movement the Feet and Toes
Similar to the thigh muscles, the muscles of the leg are divided past deep fascia into compartments, although the leg has three: anterior, lateral, and posterior (Figure eleven.32 and Effigy 11.33).
Effigy 11.32 Muscles of the Lower Leg The muscles of the anterior compartment of the lower leg are by and large responsible for dorsiflexion, and the muscles of the posterior compartment of the lower leg are generally responsible for plantar flexion. The lateral and medial muscles in both compartments invert, evert, and rotate the foot.
Figure eleven.33 Muscles That Move the Feet and Toes
The muscles in the anterior compartment of the leg: the tibialis anterior, a long and thick muscle on the lateral surface of the tibia, the extensor hallucis longus, deep under it, and the extensor digitorum longus, lateral to information technology, all contribute to raising the front of the pes when they contract. The fibularis tertius, a pocket-size musculus that originates on the anterior surface of the fibula, is associated with the extensor digitorum longus and sometimes fused to it, simply is non present in all people. Thick bands of connective tissue called the superior extensor retinaculum (transverse ligament of the talocrural joint) and the inferior extensor retinaculum, concur the tendons of these muscles in place during dorsiflexion.
The lateral compartment of the leg includes two muscles: the fibularis longus (peroneus longus) and the fibularis brevis (peroneus brevis). The superficial muscles in the posterior compartment of the leg all insert onto the calcaneal tendon (Achilles tendon), a potent tendon that inserts into the calcaneal bone of the talocrural joint. The muscles in this compartment are large and strong and go on humans upright. The about superficial and visible muscle of the calf is the gastrocnemius. Deep to the gastrocnemius is the broad, flat soleus. The plantaris runs obliquely between the ii; some people may have two of these muscles, whereas no plantaris is observed in near 7 percent of other cadaver dissections. The plantaris tendon is a desirable substitute for the fascia lata in hernia repair, tendon transplants, and repair of ligaments. There are 4 deep muscles in the posterior compartment of the leg every bit well: the popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior.
The foot besides has intrinsic muscles, which originate and insert within it (similar to the intrinsic muscles of the manus). These muscles primarily provide back up for the foot and its arch, and contribute to movements of the toes (Figure 11.34 and Effigy 11.35). The principal back up for the longitudinal curvation of the foot is a deep fascia called plantar aponeurosis, which runs from the calcaneus os to the toes (inflammation of this tissue is the cause of "plantar fasciitis," which can affect runners. The intrinsic muscles of the foot consist of ii groups. The dorsal group includes simply one muscle, the extensor digitorum brevis. The 2d group is the plantar grouping, which consists of four layers, starting with the nearly superficial.
Figure 11.34 Intrinsic Muscles of the Foot The muscles along the dorsal side of the foot (a) generally extend the toes while the muscles of the plantar side of the pes (b, c, d) mostly flex the toes. The plantar muscles exist in three layers, providing the foot the strength to counterbalance the weight of the body. In this diagram, these three layers are shown from a plantar view beginning with the bottom-virtually layer only under the plantar peel of the foot (b) and ending with the top-most layer (d) located just inferior to the foot and toe bones.
Figure 11.35 Intrinsic Muscles in the Foot
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Source: https://openstax.org/books/anatomy-and-physiology/pages/11-6-appendicular-muscles-of-the-pelvic-girdle-and-lower-limbs
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